The present invention generally relates to logical device backups.
Types of logical volume include, for example, a real volume that is formed based on the storage space of one or more storage devices (logical volumes of a real entity), and virtual volumes based on Thin Provisioning technology (virtual logical volumes). A storage area that constitutes a real volume (‘real area’ hereinbelow) is assigned to a virtual storage area (‘virtual area’ hereinbelow) in a virtual volume and data is written to the real area (Japanese Application Laid Open No. 2006-338341, for example). Data fragments which are stored in the real area assigned to the virtual volume can be copied to the real volume (Japanese Application Laid Open No. 2007-102455, for example).
Cases where a virtual volume that is undergoing a backup is utilized can arise. Hence, it is necessary to be able to restore a virtual volume undergoing a backup.